Provide access to root URI from TestRestTemplate

Closes gh-10641

spring-boot-project/spring-boot-test/src/main/java/org/springframework/boot/test/web/client/TestRestTemplate.java

@@ -78,6 +78,7 @@ import org.springframework.web.util.UriTemplateHandler;
  * @author Dave Syer
  * @author Phillip Webb
  * @author Andy Wilkinson
+ * @author Kristine Jetzke
  * @since 1.4.0
  */
 public class TestRestTemplate {
@@ -165,6 +166,15 @@ public class TestRestTemplate {
 		this.restTemplate.setUriTemplateHandler(handler);
 	}
 
+	public String getRootUri() {
+		UriTemplateHandler uriTemplateHandler = this.restTemplate.getUriTemplateHandler();
+		if (RootUriTemplateHandler.class
+				.isAssignableFrom(uriTemplateHandler.getClass())) {
+			return ((RootUriTemplateHandler) uriTemplateHandler).getRootUri();
+		}
+		return "";
+	}
+
 	/**
 	 * Retrieve a representation by doing a GET on the specified URL. The response (if
 	 * any) is converted and returned.

spring-boot-project/spring-boot-test/src/test/java/org/springframework/boot/test/web/client/TestRestTemplateTests.java

@@ -63,6 +63,7 @@ import static org.mockito.Mockito.verify;
  * @author Phillip Webb
  * @author Stephane Nicoll
  * @author Andy Wilkinson
+ * @author Kristine Jetzke
  */
 public class TestRestTemplateTests {
 
@@ -81,6 +82,31 @@ public class TestRestTemplateTests {
 				.isInstanceOf(HttpComponentsClientHttpRequestFactory.class);
 	}
 
+	@Test
+	public void getRootUriRootUriSetViaRestTemplateBuilder() {
+		String rootUri = "http://example.com";
+		RestTemplate delegate = new RestTemplateBuilder().rootUri(rootUri).build();
+
+		assertThat(new TestRestTemplate(delegate).getRootUri()).isEqualTo(rootUri);
+	}
+
+	@Test
+	public void getRootUriRootUriSetViaLocalHostUriTemplateHandler() {
+		String rootUri = "http://example.com";
+		TestRestTemplate template = new TestRestTemplate();
+		LocalHostUriTemplateHandler templateHandler = mock(
+				LocalHostUriTemplateHandler.class);
+		given(templateHandler.getRootUri()).willReturn(rootUri);
+		template.setUriTemplateHandler(templateHandler);
+
+		assertThat(template.getRootUri()).isEqualTo(rootUri);
+	}
+
+	@Test
+	public void getRootUriRootUriNotSet() {
+		assertThat(new TestRestTemplate().getRootUri()).isEqualTo("");
+	}
+
 	@Test
 	public void authenticated() {
 		assertThat(new TestRestTemplate("user", "password").getRestTemplate()